Embolic device delivery system with retractable partially coiled-fiber release

ABSTRACT

A medical device for placing an embolic device, such as an embolic coil, at a predetermined site within a vessel of the body including a delivery catheter and a flexible pusher member slidably disposed within the lumen of the catheter. An embolic device having a headpiece coupled to the proximal end is releasably disposed within the distal end of the pusher member and retained in place by a retractable fiber, having a coiled distal portion. When the embolic device is advanced to the predetermined site within the vessel, the detachment fiber is retracted from around the headpiece of the embolic device to thereby release the embolic device.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates to a medical device for placing an embolicdevice, such as an embolic coil, at a predetermined site within avessel, and more particularly relates to a catheter based deploymentsystem for delivering an embolic coil. This device is particularlysuited to transport an embolic device, through the tortious vasculatureof the human brain and to the predetermined site within the vessel.

2. Description of the Prior Art

For many years, flexible catheters have been used to place variousdevices within the vasculature of the human body. Such devices includedilation balloons, radiopaque fluids, liquid medications, and varioustypes of occlusion devices such as balloons and embolic coils. Examplesof such catheter-based devices are disclosed in U.S. Pat. No. 5,108,407,entitled “Method and Apparatus for Placement of an Embolic Coil;” andU.S. Pat. No. 5,122,136, entitled “Endovascular ElectrolyticallyDetachable Guidewire Tip for the Electroformation of Thrombus inArteries, Veins, Aneurysms, Vascular Malformations and ArteriovenousFistulas.” These patents disclose catheter-based devices designed todeliver embolic coils to a predetermined site within a vessel of thehuman body in order to treat aneurysms, or alternatively, to occlude ablood vessel at a particular location.

Coils which are placed in vessels may take the form of helically woundcoils, or alternatively, may take the form of randomly wound coils,coils wound within coils or other such coil configurations. Examples ofvarious coil configurations are disclosed in U.S. Pat. No. 5,334,210,entitled “Vascular Occlusion Assembly;” and U.S. Pat. No. 5,382,259,entitled, “Vasoocclusion Coil with Attached Tubular Woven or BraidedFibrous Covering.” Embolic coils are generally formed of a radiopaquemetallic material, such as platinum, gold, tungsten, or an alloy ofthese metals. Often, several coils are placed at a given location toocclude the flow of blood through the vessel or aneurysm by promotingthrombus formation at the particular location.

Additionally, embolic coils have been placed within the distal end of acatheter, such that when the distal end of the catheter is properlypositioned, the coil may then be pushed out of the end of the catheterwith a pusher member to release the coil at the predetermined sitewithin the vessel. This procedure for placement of the embolic coil isconducted under fluoroscopic visualization, such that the movement of acoil through the vasculature of the body may be monitored, and the coilmay be placed in the desired location.

Another procedure involves the use of glue or solder to attach the coilto a guidewire, which is then placed within a flexible catheter forpositioning the coil at a predetermined site within the vessel. Once thecoil is at the predetermined site, the catheter holds the coil inposition, and the guidewire is pulled proximally of the catheter tothereby detach the coil from the guidewire. Such a coil positioningsystem is disclosed in U.S. Pat. No. 5,263,964 entitled, “CoaxialTraction Detachment Apparatus and Method.”

Still another coil positioning procedure is that of having a catheterwith a socket at the distal end, such that it retains a ball that isbonded to the proximal end of the coil. The ball, generally larger indiameter than the outside diameter of the coil, is placed in a socketwithin the lumen at the distal end of the catheter, and the catheter isthen moved into a vessel in order to place the coil at a predeterminedlocation. Once the site is reached, a pusher wire with a piston at theend thereof is pushed distally from the proximal end of the catheter topush the ball out of the socket, in order to release the coil at thepredetermined site. Such a system is disclosed in U.S. Pat. No.5,350,397, entitled, “Axially Detachable Embolic Coil Assembly.”

Another procedure for placing an embolic coil at a predetermined sitewithin a vessel is that of using a heat releasable adhesive bond forretaining the coil at the distal end of the catheter. One such systemuses laser energy transmitted through a fiber optic cable to apply heatto the adhesive bond in order to release the coil from the distal end ofthe catheter. Such a procedure is disclosed in aforementioned U.S. Pat.No. 5,108,407.

Still another coil deployment system incorporates an interlockingmechanism with the coil. The interlocking end of the embolic coilcouples with a similar interlocking end on a pusher assembly. A controlwire extends through the two interlocking ends to secure the coil to thepusher assembly. The pusher assembly and embolic coil are initiallydisposed within the lumen of a catheter. When the embolic coil is pushedout of the end of the catheter for placement, the control wire isretracted and the coil disengages from the pusher assembly. Such adeployment system is disclosed in U.S. Pat. No. 5,925,059, entitled,“Detachable Embolic Coil Assembly.”

Yet another coil deployment system incorporates an embolic devicedetachably mounted on the distal portion of a pusher member and held inplace with a connector thread or fiber. The fiber passes through acutter member that may be activated to cut the connector fiber. Once theconnector fiber is cut, the embolic device is released. Such adeployment system is disclosed in Published U.S. Patent Application No.2002/0165569, and entitled, “Intravascular Device Deployment MechanismIncorporating Mechanical Detachment.”

Still another coil deployment system incorporates an embolic device witha stretch resistant member therethrough. The distal end of the stretchresistant member is attached to the embolic coil, and the proximal endof the stretch resistant member is detachably mounted on an elongatedpusher member to allow for placement and release of the coil within avessel. The stretch resistant member is detachably mounted on the pushermember through various means, such as adhesive or by a connector fiberadhered to or tied onto the pusher member and is detachable by theapplication of heat. Such a deployment system is disclosed in PublishedU.S. Patent Application No. 2004/0034363, entitled, “Stretch ResistantTherapeutic Device.”

Still another coil deployment system incorporates a platinum wire and ortip that is inserted into a vascular cavity. The tip may be elongatedand flexible, folded upon itself several times, or may have a branchedconfiguration. The tip may be separated from the wire mechanically orvia electrolytic separation. Such a system is disclosed in U.S. Pat.Nos. 5,540,680; 5,895,385; 5,925,037; and 5,976,126, all entitled,“Endovascular Electrolytically Detachable Wire and Tip for the Formationof Thrombus in Arteries, Veins, Aneurysms, Vascular Malformations, andArteriovenous Fistulas.”

Still another coil deployment system incorporates a pusher member,having a stiff wavy-shaped wire end segment, coupled to an embolic coiland placed within the lumen of the catheter. The coil is advancedthrough the catheter until it reaches the predetermined site within thevessel, at which time the pusher member is retracted and the emboliccoil is released. Such a system is disclosed in U.S. Pat. No. 6,203,547,entitled, “Vaso-occlusion Apparatus Having a Manipulable MechanicalDetachment Joint and a Method for Using the Apparatus.”

Still another embolic device deployment system includes an elongatedflexible pusher member slidably disposed within a lumen of a catheter.An embolic device is retained at the end of the pusher member with adetachment filament. When the embolic device is advanced to thepredetermined site within the vessel, the detachment filament iswithdrawn releasing the embolic device. Such a system is disclosed inU.S. patent application Ser. No. 11/145,350 filed on Jun. 3, 2005,entitled, “Embolic Device Deployment System with Filament Release.”

SUMMARY OF THE INVENTION

The present invention is directed toward a vasooclusive embolic devicedeployment system for use in placing an embolic device at apredetermined site within a vessel including an elongated flexiblecatheter and an elongated pusher member slidably disposed within thelumen of the catheter. Disposed at the distal end of the pusher memberis an embolic device having a headpiece with a cylindrical outersurface.

In accordance with an aspect of the present invention a retractablefiber, preferably formed of nitinol, includes a distal section, which issufficiently stiff to maintain a preshaped configuration. This distalsection is pre-shaped into a coiled configuration. When the fiber ispulled proximally the coiled configuration stretches to return to agenerally straight configuration, to thereby release the embolic deviceat the predetermined treatment site within the vessel. The retractablefiber extends from a position proximal of the proximal end of the devicethrough the lumen of the catheter and around the headpiece of theembolic device. The retractable fiber may fill the luminal space aroundthe headpiece of the embolic device, such that the embolic device isfrictionally held until a proximal force is applied to the fiber.

In accordance with another aspect of the present invention, the pushermember includes a lumen therethrough, and the embolic device is slidablydisposed within the lumen at the distal end of the pusher member. Theretractable fiber extends from a position proximal of the proximal endof the pusher member, through the lumen of the pusher member and aroundthe outer surface of the headpiece of the embolic device. The fiber mayfill the luminal space around the headpiece of the embolic device isheld frictionally within the lumen at the distal end of the pushermember.

In accordance with yet another aspect of the present invention, areleasable clamp having a lumen extending therethrough is mounted on theproximal end of the pusher member. The detachment fiber extends throughthe lumen of the clamp, so that upon release of the clamp theretractable fiber may be pulled proximally to unwind it from around theheadpiece of the embolic device at the predetermined site within thevessel.

These aspects of the invention and the advantages thereof will be moreclearly understood from the following descriptions and drawings of apreferred embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged, partially sectional view of an embodiment of anembolic device deployment system in accordance with the presentinvention; and,

FIGS. 2 a, 2 b, and 2 c are enlarged, sectional views of the distal endof coil deployment system shown in FIG. 1, illustrating the sequentialsteps in the advancement of the embolic device, removal of a retractablefiber, and release of an embolic device at the predetermined treatmentsite within the vessel.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 generally illustrates one embodiment of a retractable detachmentfiber arrangement of an embolic device deployment system 10 of thepresent invention including an elongated flexible catheter 12 having alumen 14 therethrough. An elongated flexible pusher member 16, having aproximal end 18 a distal end 20 and a lumen therethrough 22, is slidablydisposed within the lumen 14 of the catheter 12. Preferably, the pusher16 is constructed from Nitinol, but alternatively may be constructedfrom any flexible, biocompatible material, such as stainless steel,nylon, PTFE, other flexible materials, polymers, or composites.

An embolic device 24 having a proximal end 26 and a distal end 28,preferably taking the form of a helically wound embolic coil, isdisposed within the lumen 22 of the distal end 20 of the pusher member16. Alternatively, the embolic device may take the form of embolicfilaments, braids, expandable meshes, foams and stents. Coupled to theproximal end 26 of the embolic device 24, there is a headpiece 30,preferably, having a cylindrical outer surface. The headpiece 30 of theembolic device 24 extends distally into the embolic device, as well as,proximally from the embolic device 24 into the lumen 22 of the distalend 20 of the pusher member 16. Additionally, a releasable clamp 32,preferably taking the form of Tuohy Borst connector, having a proximalend 34 and a distal end 36, is mounted on the proximal end 18 of thepusher member 16.

An elongated retractable fiber 38 is constructed, preferably, fromNitinol but may also be constructed from platinum, nylon, PTFE, or otherflexible metals, polymers, or composites. Extending from a positionproximal of the proximal end 34 of the clamp 32, the elongatedretractable fiber 38 extends through the clamp 32, which maintainstension on the fiber 38. The retractable fiber 38 then extends throughthe lumen 22 of the pusher member 16, from the proximal end 18 towardthe distal end 20, and around the outer surface of the headpiece 30 ofthe embolic device 24, preferably in a coiled configuration 40.

In order to prevent the fiber 38 from prematurely disengaging fromaround the headpiece of the embolic device, the clamp 32 maintainstension on the fiber 38. To allow for application of a proximal force tothe fiber 38, the clamp 32 is loosened, such that the fiber may bewithdrawn from around the outer surface of the embolic device 24 and theembolic device may be released at the predetermined site in the vessel.

FIGS. 2 a, 2 b, and 2 c generally illustrate the operation of theembolic device deployment system 10 and demonstrate the retractablefiber release mechanism of the present invention. More particularly,FIG. 2 a illustrates the catheter 12 positioned at a predeterminedlocation analogous to placement in a vessel and the pusher member 16advanced, such that the embolic device 24 exits the distal end of thecatheter. Also, illustrated in more detail is the path of theretractable fiber 38 around the headpiece 30 of the embolic device 24.The fiber extends through the lumen 22 of the pusher member 16 towardand subsequently around the headpiece 30 of the embolic device 24.Preferably, the detachment fiber 38 fills the luminal space around theouter surface of the headpiece 30 of the embolic device 24 in the coiledconfiguration 40 to frictionally hold the embolic device 24 within thedistal end 20 of the lumen 22 of the pusher member 16. The coiledconfiguration 40 of the retractable fiber 38 may be pre-shaped, or,alternately, shaped around the headpiece as is necessitated by thematerial used to construct the fiber 38.

FIG. 2 b illustrates the embolic device deployment system 10 of thepresent invention after proximal force has been applied to theretractable fiber 38, such that the retractable fiber 38 is partiallydisengaged from around the outer surface of the headpiece 30 of theembolic device 24. The coiled configuration 40 of the retractable fiber38 need not straighten completely as proximal force is applied to thefiber 38. Such a coiled fiber configuration allows for a minimalproximal force to be used to disengage the coiled configuration 40 ofthe retractable fiber 38 from around the outer surface of the headpiece30 of the embolic device 24.

FIG. 2 c illustrates the coiled configuration 40 of the retractablefiber 38 further stretched, such that the detachment fiber 38 iscompletely disengaged from around the outer surface of the headpiece 30of the embolic device 24. After the detachment fiber 38 is completelydisengaged from around the outer surface of the headpiece 30, theembolic device 24 is no longer held frictionally within the lumen 22 ofthe distal end 20 of the pusher member 16, thereby releasing the embolicdevice 24 at the predetermined treatment site within the vessel.

One of the important advantages of the present invention is that theembolic device may be placed at a desired location within a vessel, orwithin an aneurysm, with the configuration of the device deploymentsystem as shown in FIG. 2 a. If it is determined that the embolic deviceis improperly positioned, the embolic device 24 may then be withdrawnfrom that location and placed at another location, or even removed fromthe body by first withdrawing the pusher member 16 and the embolicdevice totally back into the catheter. Once the embolic device has beenentirely withdrawn back into the delivery catheter, the catheter maythen be moved to a more desirable location and the embolic device maythen be released at the new location.

As is apparent, there are numerous modifications of the preferredembodiment described above which will be readily apparent to one skilledin the art, such as many variations and modifications of the embolicdevice including numerous coil winding configurations, or alternatelyother types of implant devices. There are variations in theconfiguration of the distal section of the retractable fiber as well asvariations in the material and flexibility of the proximal portion ofthe detachment fiber. Additionally, there could be variations the methodin which tension is applied to the retractable fiber at the proximal endof the device. These modifications would be apparent to those havingordinary skill in the art to which this invention relates and areintended to be within the scope of the claims which follow.

1. A vasooclusive embolic device deployment system for use in placing anembolic device at a predetermined site within a vessel comprising: anelongated flexible catheter having proximal and distal ends and a lumenextending therethrough; an elongated pusher member having proximal anddistal ends and a lumen extending therethrough, and being slidablydisposed within the lumen of the catheter; an embolic device havingproximal and distal ends, having a headpiece disposed within theproximal end of said embolic device, said headpiece having a cylindricalouter surface, and said embolic device being slidably disposed withinthe lumen of the distal end of the pusher member; and, an elongatedretractable fiber including a distal section which is sufficiently stiffto maintain a pre-shaped configuration, but when pulled proximallystretches to return to a generally straight configuration, said distalsection being formed into a generally coiled configuration, saidretractable fiber extending from a position proximal of the proximal endof the pusher member, through the lumen of the pusher member and saidcoiled distal section extending around the cylindrical outer surface ofthe headpiece of the embolic device, filling the luminal space aroundthe headpiece and holding the embolic device frictionally within thedistal end of the pusher member, until a proximal force is applied tothe fiber to withdraw said coiled distal section from around theheadpiece of the embolic device to thereby release the embolic device atthe predetermined site within the vessel.
 2. A vasooclusive embolicdevice deployment system as defined in claim 1, wherein a releasableclamp having a lumen therethrough is mounted on the proximal end of thepusher member, said retractable fiber extending through the lumen of theclamp so that upon release of the clamp the detachment fiber may bepulled proximally to release the embolic device.
 3. A vasooclusiveembolic device deployment system as defined in claim 1, wherein saidretractable fiber is formed of nitinol.